It’s always worrying to have a computer virus.
Who knows what it’s doing down there in the distant recesses of your computer?
It could be making things not work correctly, making ads pop up randomly, or even stealing your passwords.
And that’s just on your computer that you know is infected, you also have to be concerned with any connections made to that computer – it could be emailing itself to your friends, or spreading through your local network.
But could it go through your HDMI cable to your projector?
You wouldn’t want to go through the whole process of removing it from your computer and other devices, just to have it maliciously lurking in your projector, waiting to strike next time you unsuspectingly plug in and try to watch a movie.
Is it possible?
For a computer virus to go from your computer to your projector, two things would need to be true:
- The virus would need to be able to transfer itself over HDMI (or potentially another video cable format)
- The virus would need to be able to survive in the projector
Let’s discuss each of them.
Can a Computer Virus be Transmitted over HDMI?
HDMI stands for “High Definition Multimedia Interface”. It is an audio / video interface to transmit audio and video data from a source device to a monitor, projector, or other receiver device.
This source – receiver distinction is important because this means the connection is typically one way. Note that this does not mean the cables are one way, just that the ports on your computer or projector will almost certainly be either exclusively sending or receiving ports, but not both.
So you are probably safe from the virus coming back to your computer over your HDMI cable, but is it possible to send a virus from the source device (your computer) to the projector?
The answer is, maybe but it would be very difficult and only work with specific hardware.
Most data sent over HDMI is specifically audio or video data, which can’t really spread viruses because it’s interpreted in a very specific way by the receiving hardware, but there is a communications channel in HDMI that, if your projector supported it, could theoretically allow someone to control it from your computer, or send a virus to it.
It’s called Consumer Electronics Control, if you’re curious.
Can a Computer Virus Survive in a Projector?
A computer virus, in its common usage, is a program that you don’t want on your computer, doing something undesirable.
What’s important here, is that it is a program, and therefore a piece of software. It needs storage to live in, and it needs some sort of processor to execute it, otherwise it can’t ever really exist somewhere.
In a simple projector or other video output device, the video and audio signals come in, and are displayed / played immediately.
This means that such devices aren’t really vulnerable to computer viruses because there’s no storage, and no processor, so the virus has nowhere to live and nothing to execute it.
But, more often than not, modern projectors are “smart”. This means that in addition to just displaying video and audio sent in externally, the projector has its own intelligence and storage, which enable smart features like apps, voice commands, and movie streaming services, all on the actual projector.
These devices are certainly capable of hosting a computer virus! However, this isn’t as big of a threat as you might think.
There’s a couple reasons why there aren’t a lot of viruses out there for smart devices.
- Since each smart device manufacturer is running its own proprietary software, you can’t just write one virus for everything – most viruses have to be carefully designed for their specific environment.
- The device manufacturer will have measures in place to prevent against viruses – for instance they can make the storage “read only”
So can your infected computer give your projector a virus?
Technically, it is possible. In a very specific set of circumstances, it is theoretically possible to do this.
But is anyone going to bother going to all this effort? It seems unlikely. It would be a real challenge to get it to work, and it would be dependent on particular hardware, and at the end of the day, what can you really do with a projector?
If you put yourself in the shoes of someone making these viruses, it’s going to be a lot more worth their time to make something that spreads through more traditional means.
I wouldn’t worry about this too much.